In known systems, such as ground reference antennas used in Local Area Augmentation Systems (LAAS) and Ground Based Augmentation Systems (GBAS), generally the feed network board is kept outside of the antenna in its own independent box. The feed network then connects to each antenna element through RF cables of a specific length to maintain the same phase delay to each antenna element.
Some current implementations of LAAS/GBAS antenna arrays include several parasitic elements. This increases the cost and complexity of such designs. Feed networks for such antenna arrays are difficult to produce and most feed networks require complex driving boards and numerous phase stable cables to maintain acceptable phase stability. Some current feed networks use microstrip lines and striplines, but issues common to both approaches persist. These issues include the need for enough space in the feed networks to isolate strong and weak signals; coupling the feed network to actual feed lines; and the need for complex assembly processes.